In our old house, we had ikea butcher block countertops that we treated with tung oil. For low cost and great quality, I loved them; and when we redo or current house we will probably use ikea butcher block again.
I treated them about every month or so with pure tung oil we bought at a woodworkers supply place. (do your research before you choose a finish - we liked tung oil because it is food safe, self-polymerizes, and leaves a lovely warm sheen)
When we instaleld them, I did a couple coats of sanding and oiling on the underside before installation. After install, i sanded and oiled the tops until kingdom come, to get the surface as smooth as possible. If you use tung oil, you have to mask off the backsplash, or be very careful, because the oil cures hard when it polymerizes, and wont wipe off easily. This isn't such a problem for the upkeep oiling because it is the centers of the countertop, subject to moisture and use, that need oil added regularly.
Unfortunately, I don't have any pictures of our counters handy, but this renovation I found on Brick and Brack is beautiful, and they have a great deoscription of how they used the tung oil on their ikea numerar, to boot.
|Brick and Brack Butcher Block with Tung Oil|
The one area i did have some small issues with splitting/cupping was around our stainless steel inset sink. In our next kitchen, i might make the counters surrounding the sink something other than butcher block, or maybe have a sink with a larger rim.
Good luck! Let me know if you have any other questions.
p.s. the folks at the gardenweb kitchen forum are another great resource for home reno questions.